Magneto



3 SheetsfSheet l W. F. SMITH MAGNETO Flled Dec. 5.

July 19, 1927.

sr/f) y /LTTR/VEY Patented July 19, 1.927.

UNITED STATES PATENToFFICE.-

WHILIAH l'. SMITH, 0F POUGHXEEPBIE, NEW YORK, ASSIGNOB 0l ONE-HAL' HIM A. BCHATZ, OF POUGHKEEPSIE, NEW YORK.

menare'.

yApplication' med December 5, 1924. Serial llo. 754,114.

'proved automatic ignition timing` means, andv other features described in the following detailed description and the appended claims. The invention is disclosed as applied to the crank-shaft of a single cylinder internal combustion engine and a tractor propelled by it described and claimed in my copending applications, Serial Nos. 722,580 and 15,338, filed June 26, 1924 and May 23, 1924, respectively. It will be obvious, however, to those,

skilled in the art1 that the various features of the invention are capable of a wide variety of different uses without departfng from its spirit. y

' The referred embodiment of the invention is lllustrated in the drawings in which Fig. 1 is a plan view of the magneto structure; Fig. 2 isl a sectional view along lines 2-2 of Fig. 1; Fig. 3 illustrates in vertical cross-section the ma neto mounted on an extension of the cran -shaft of an internal combusiton engine; Fig. 4is an enlarged view of the spark advance controlling mechanism; Fig. 5 illustrates'in plan view a modified structure; and Figs. 6 and 7 are illustrations of two circuit dia ams adapted for use in conjunction with i e magneto.

Referring now to Fig. 1 and 2 of the drawings, a substantially circular permanent magnet 1 mounted on an extension 2 of the crank-shaft is arranged to rotate therewith in the direction of the arrow. The ends of the permanent ma net 1 are separated by an air-gap 3, these en s being formed into polepieces 4 and 5. Instead of attaching separate polepieces to the permanent magnet l, the ends of the magnet are u set at 6 and 7, raising the inner faces of t e polepieces 4 and 5 into close proximity with pole heads 8 and 9 of the armature lcores 10 and.11. The laminated pole heads 8 and 9 form a unitary structure with the cores which are built up of iron laminations in the form of stampmgs of a contour clearly illustrated in Flg. 1. The laminations are held together by means of rivets 12, and the u l er ends of the core laminations are dove-tailldd into the ends of a laminated yoke 14. The laminations of the yoke are riveted together at 13.

Coils 15 and 16, each comprising rimary and secondary windings, surround t e cores 10 and 11. The coils are provided with spool heads 17, 18 and 19, 20 of insulating material. A bracket 21 carr ing-:ian adjustable contact point 22 is rivetedy to the spool head 18 at 23. The contact 22 cooperates with contactl 24 carried by a leaf spring 25, the two ends of which are riveted res ectively, to the spool heads 19 and 20. e spring 25 has two upturned flanges 26 tov glve it rigidity, the spring being normally pressed `with its contact 24 into engagement with the contact 22 by means of a leaf spring 27 riveted to the underside of the spool head 20. A condenser 28 is held between the pole heads 8 `and 9 within recesses such as 29 prov1ded by cutting away'A portions of some of the lammations that go to make up the pole heads 8 and 9.

Referring now to Fig. 3, the manner inv which the magneto is mounted on an extension 2 of the crank-shaft 30 of an internal combustion engine will be ex lained. The permanent magnet 1 is held y means of screws like 50 against a casting 51 of aluminum or other non-magnetic material which `in turn is secured by means of screws like 54 to a casting 52 keyed to the shaft 2 at 53.

The castings 51 and 52 (the outside surface of the latter serving as a belt-drive) rotate therefore with the shaft 2. The armature core is fastened by means of screws 31 and 32 into bushings 55 and 56 projecting from a casting 57 of non-magnetic material. The screwsproject through the pole heads 8 and 9 and the ends of yoke 14. The casting 57 is rigidly held against the crank-shaft casing 58 by means of bolts like 59. The casing 58 'is' stationary with respect to shaft 30 which is free to rotate within a sleeve bearing 61 provided in the casing. It should be noted in' this connection that the whole magneto structure is made accessible for inspection or repair simply by removing casting 52 without dismantling the, internal combustion engine.

The key 53 serves also to fasten to the 110 M 71 and the latter. is supported only by the three pinions 68 intermeshing therewith. Each guard of the pinions 68 is provided with an arm 75, and a weight 76 is carried between the ends of each pair of arms. A cam 77, built up of fibre or other insulating laminations and `adapted to en age the spring is fastened to the gear 71 iy means of rivets 78.

During the rotation of the shaft 2 the casting 51 is caused to rotate with the permanent magnet 1, the polepieces 4 and 5 of f dicated which, in passing by the pole heads 8 and 9 of the armature cause, in the well-known manner, the magnetic flux to pass through the core 10, 11 and yoke l14, and this in turn results in 4the generation of alternating current fluctuations in the secondary windings, and by induction, with primary windings of coils 15 and 16. The pole pieces 4 and 5 are so dimensioned that the span the gap 3 between the pole heads 8 andY magnetic flux is short-circuited twice during each revolution of the permanent magnet 1. Inasmuch as the electrical characterist-ics of such magneto structures are well known in the art, their description will be dispensed with. It should be noted, however, that owing to the type of magnet structure used, losses which result from interruptions in the magnetic circuit when separate polepieces are fastened to the ends of the permanent magnet are entirely avoided by forming the polepieces 4 and 5 homogeneously -with the magnet 1. The magnet 1 and the armature structure being rigidly mounted on heavy castings, the maintenance of a very narrow air-gap between the polepieces and the pole heads is insured. In order toprevent the setting up of an opposing flux through thecores 10 and 11 when one polepiece of the permanent magnet 1 passes by a pole head and the other polepiece by the upper end of the core (see Fig. 1 in which the path of the polepieces is inin a dotted circle), iron shields 79 and 80 are provided. These shields are in the form of strips, the ends of which are fastened to the spool heads 17, 18 and 19, 20, respectively, and serve to afford a shunt path for the magnetic flux when the polepieces 4 and 5 pss near the ends of such shields.

.The sleeve 63 being also rotated with the shaft 2 will drive the gear 71, through the 9, whereby thel .upward by the leaf spring 27, it will force these springs down, causing the opening of the primary circuit in contacts 22 and 24.

The arms are normally h eld down by means of springs 81 wound around the heads of the brackets 64, 65 'and 66 and having 75 their ends attached to the arms 75 and brackets 64, 65 and 66, respectively. When the speed of rotation of shaft 2 is increased then owing to the centrifugal action of the weight 76, the arms 75 will be moved into 80 or towards the positions indicated in dotted lines in Fig. 4. Such movement of an arm 7 5 will cause the associated pinion 68 to rotate, which movement is transmitted to the gear 71. The gear 71 is thus caused to ad 85 vance in addition to the above described ro,- tary motion normally im arted by the pinions, whereby thc cam 7 will engage the spring 25 at a point. to the left of the one indicated in Fig. 1. on the speed at which the shaft 2 is rotated, i. e., on the speed of the internal combustion engine the opening of the primary circuit is automatically timed to occur at more or' less advanced positions of the crank-shaft and therefore of the ried by this shaft.

The automatic spark advance arrangement is provided in a manner to make possible a piston or pistons carsimple and compact arrangement. The gear |00 71 being out of Contact with shaft 2, oiling of lthe parts which would detrimentally affect the electrical contacts is avoided. Furthermore, the predetermined setting of gear 71 and the pinions 68 is not disturbe.'l by mi wear, as wou d be the'case if some solid coupling were provided between the shaft and the gear. Another im ortant feature of this arrangement consists 1n that the relative adjustments of the armature and magnet are im not interfered with by its operation.

The electrical circuit connections may be provided in any one of a plurality of suitable combinations. Fig. 6 illustrates a circuit in which the primary coils 90, 91 are H5 connected in series with the interru ter springs 22, 24, the latter being shunte by means of condenser 28 to eliminate sparking. The secondary coils,.92, 93 are also connected in series and each with one electrode of l2cspark plugs 94 and 95 the other electrodes of these plugs being grounded.

In the circuit diagram illustrated in Fig. 7, the primary coils 90 and 91 are connected in parallel with each other and with the contacts 22 and 24.

Fig. 5 illustrates the manner in which four coils 96, 97, 98 and 99 may be mounted in the structure herein disclosed, the dotted lines indicating where the cores and pole 13o Depending, therefore, 90

65 being ing/meshwith the teeth of said three Aheads of adjacent coils come in contact with net carried by said shaft, a stationary armature, contacts in the 'armature circuit, and means comprising a gear and pinion responsive to the speed at which said shaft.' rotates for opening said vcontacts in different rota-ry positions of said shaft.

2. In a magneto, a shaft, means forrotating said shaft at varying s eeds, a stationary armature, contacts 1n t e armature circuit, a gear rotating at the speed of said shaft but free to revolve with respect there-" to, a cam carried by said gear for opening said contacts, and means responsive to the speed at which said shaft rotates for causing said gear .to revolve' independently of said shaft.

3. In a magneto, a shaft, means for rotating said shaft at varying speeds, a stationary armature, contacts in the amature s clrcuit, a pinion carried by said shaft Vand revolving therewith, means responsive to the speed of said shaft for rotating said pinion relative to said shaft, a gear mtermeshinr with said pinion, anda cam carried by said gear for actuating said contacts.

4. In a magneto, a shaft, means for rctating said shaft at varying speeds, a stationary armature, contacts in the armature circuit, a rotating element, a cam carried thereby for actuating said contacts, another element fastened to said shaft and in operative contact with said rotatin element, and means responsive to the s of said shaft for rotating said other e ement to displace said rotating element. i

5. In a magneto, a rotating shaft, a magnet carried thereby, an amature including a primary and a secondary winding, contactsin the circuit of saidl primary winding three pinions fastened to said shaft, a gear supported by and intermeshing with said'pinlons, ,and means carried by said gear for actuating said contacts.

6. In a magneto, a rotating shaft, a substantially circular permanent ma et surrounding said shaft and carried t ereby, a stationary armature including a primary and a secondary winding surrounded b saidl magnet, contacts in the circuit of sai primary winding, a sleeve fastened to said shaft, three brackets radially rojectin from said sleeve, a inion carried by eac bracket, two guard p ates of larger diameter 'than said pinions mounted on each pinion, eccentric weights carried by said guard plates, springs normally forcing said wei hts towar s said shaft, a gear provided wit Alateral shoulders surroundin said shaft but free thereof, the teeth of sald gear pinions 'and said ear being held against ateral andhverticad dislplacements by 311e c ote ar atesenang e sliglilders on sagiii geaii: a leaf sgprgiii bent `in a semi-circleand held at both en s carryin one of said contacts, and a cam fastene to said gear and adapted to engage said spring at any one of a plurality of points to cause the separating of said contacts.

7. In a magneto, an operatingshaft, means for rotating said shaft. at varying speeds, an armature circuit, contacts in said circult, a

cam arranged to o en said contacts during each revolution o said shaft, and means comprising a gear and pinion responsive to the speed at which said shaft rotates for causing said cam to actuate said contacts 1n varying angular positions of said shaft.

8. In a magneto, a magnet, an armature comprising a core and a coil mounted thereon, insulating spool heads for said co1l,'a contact in the armature circuit, and a spring vcarrying said contact fastened with its two ends to said Spool heads.

9. In a magneto, a magnet, an armature comprising two coils, spool heads for said coils, two cooperating contacts" in thearmature circuit, a bent leaf spring carrying one of said contacts fastened with its two ends to two spool heads, and abracket carrying lhe (pther contact fastened to another spoo 10. In a'magneto, a substantially circula; permanent magnet the ends of which are upset to form olepieces, a laminated armature core having laminated pole heads in close proximity to said polepieces,' two coils each comprising a primary and a seconda windin mounted on said core, spool hea s of insuIating material for said coils, a leaf spring bent in a Semi-circle and having its ends riveted to the spool heads of one of said coils, acontact point carried b said leaf spring, an adjustable contact oint cooperating with said first mentions 'contact and mounted on a spool head of the other coil, and a cam for actuating said leaf spring. e y

11. In a magneto, a shaft, a magnet carried thereb an armature comprising two cores strad lingsaid shaft and surrounded by said magnet, contacts in the 'armature circuit, a s ring carxing one of said contacts parta yencirc p cam between said shaft and spring for actuating the latter.

12. 'In a magneto, a shaft, a magnet carried thereb an armature comprising two cores strad ling said shaft andsurrounded by said magnet, contacts in the armature circuit, a leaf sprin carrying one of said contacts and partial y encircling said shaft beyond the plane of said magnet, a cam between said shaft and spring for actuating the latter, and means for causing said cam to rotate around said shaft.

13. In a magneto, a substantially circular permanent magnet the ends of which are upset to form olepieces separatedfrom each other, two aminated cores parallel with eachv other, a laminated yoke interconnectin the cores at one end, laminated Dole headg on the other ends of said cores and projecting in close proximity to said polepieces, the distance between said pole heads being such that they may be spanned by a polep1ece,a coil on each core comprising a primary and a secondary winding, s ool heads of insulating material for sai coils, a magnetic shield for each core mounted on the spool heads of the associated coil, a leaf spring bent in a semi-circle and having its ends riveted to the spool heads of one ofl said coils, a contact polnt in circuit with said primary windings carried by said spring, an adjustable contact oint cooperating with said first mentioned contact, a bracket carryin said adjustable contact fastened to oney o the spool heads of the other coil, and a cam for actuating said spring.

14. In a magneto, a rotating shaft, a casing through which said shaft projects, a non-magnetic casting fastened to said casing, two parallel armature cores straddling said shaft mounted on said casting, a second non-magnetic casting overlapping said first mentioned casting and fastened to said shaft, and a permanent magnet attached to said second casting.

15. In a magneto, a ma net, an armature core, a pole head for sai core, a recess in said pole head, and a condenser held in said recess.

16. In a magneto, a magnet having two lepieces, an armature comprising two pole iigads cooperating with said polepieces, and a condenser held between said pole heads.

17. In a magneto, a magnet having polepieces, an armature comprising two opposite pole heads cooperating with said polepieces, recesses in opposite faces of Said pole heads, and al condenser fitted with its two ends in said recesses.

18. In a magneto, a rotating shaft, a casing through which said shaft projects, a disc of non-magnetic material mounted on said casing, armature core mounted on said disc, a second disc` of non-ma etic material overlapping said first mentloned disc and fastened to said shaft, and a permanent magnet attached to Said second disc.

In testimony whereof, I have signed my name to this specification this 3rd day of December 1924.

WILLIAM F. SMITH. 

